This invention relates to an apparatus and method for packaging a compressible article such as a stack of interfolded paper towels or the like.
There are a number of prior art sleeve or band-type packaging systems for packaging compressible articles, such as stacks of interfolded paper towels. In one arrangement, as shown and described in Lucas et al U.S. Pat. No. 3,729,886 (hereby incorporated by reference), the articles are compressed by opposed belts as the articles travel toward a wrapping area. A sheet is applied to one surface of the compressed stack, and is wrapped about the stack and glued together to form a band or sleeve about the compressed stack. Compression is maintained on the stack and the formed band or sleeve until the adhesive has set sufficiently to maintain the bond between the sheets when compression on the pack is released. A modification of this system involves applying a pair of sheets to the compressed stack, which are severed from a pair of webs supplied from a pair of parent rolls. The sheets are formed about the stack so that the edges of the sheets overlap, and the overlapped edges are glued together while maintaining compression on the stack. A banding or sleeving system of this type is available from the Green Bay Engineering division of Fabio Perini North America of Green Bay, Wis. under its designation Model 120. In another arrangement, which is shown and described in Haasl U.S. Pat. No. 5,367,858 (hereby incorporated by reference), a series of pairs of prongs are mounted to a pivoting turret mechanism. The prongs are moved to a collapsed position, where a partially opened sleeve is positioned over the collapsed prongs. The prongs are mounted to a turret mechanism, which pivots the prongs to an inserting station at which a compressed stack of articles is inserted into the opened sleeve. The prongs are pivoted to a removal station, at which a removing mechanism removes the stack and the sleeve from between the prongs. The stack undergoes decompression as it emerges from between the prongs, to expand into engagement with the sleeve. Several sets of prongs are mounted to the turret mechanism, which provides continuous indexing movement of the prongs between the sleeving, inserting and removal stations of the system. A banding or sleeving system of this type is available from the Green Bay Engineering division of Fabio Perini North America of Green Bay, Wis. under its designation Model 90.
The above-described banding or sleeving systems functions well and have proven to be a reliable and relatively efficient means for banding or sleeving a pack. However, each system has certain limitations. In the case of the first of the above-noted arrangements, two webs of material are supplied and wrapped about the stack, which involves support and drive components for two parent rolls of material. In addition, in order to maintain compression on the pack to allow the adhesive to set, the pack is advanced between a pair of discharge belts, which requires two sets of belt drive components. In addition, in order to operate at high speeds, a certain amount of machine length is required in order to enable the adhesive to set sufficiently prior to discharge. In the case of the second of the above-noted arrangements, the turret mechanism adds a certain amount of complexity and limits the rate at which the packs can be formed.
It is an object of the present invention to provide a band or sleeve-type packaging system for a compressible article or article, such as a stack of interfolded paper towels, which provides simplified operation and movement of the stack and the packaging material for applying the packaging material about the compressed stack. It is another object of the invention to provide such a packaging system which forms the band or sleeve from a single web of packaging material, thus eliminating the need for two separate sets of web support and drive components. It is another object of the invention to provide such a packaging system in which the band or sleeve is advanced onto the compressed stack while compression is maintained on the stack, which avoids forming the webs about the compressed stack and the necessary machine components and length required in the prior art to enable the bonded webs to set prior to discharge of the pack. Yet another object of the invention is to provide such a packaging system which is capable of operating at relatively high speeds.
In accordance with the present invention, a packaging system for packaging a compressible article, such as a stack of interfolded paper towels, includes a sleeve supply arrangement for supplying a sleeve of packaging material to a location adjacent a loading area, an article supply arrangement for positioning a compressed article in the loading area, and a sleeve advancing arrangement for advancing the formed sleeve onto the compressed article at the loading area. The article supply arrangement is movable toward and away from the loading area. After a sleeve is advanced onto the compressed article at the loading area, the article supply arrangement is moved away from the loading area. A movable stripping arrangement engages the article and the sleeve as the article supply arrangement is moved away from the loading area, to strip the article and the sleeve from the article supply arrangement. As the article and the sleeve are removed from the article supply arrangement in this manner, the article undergoes decompression, which results in the article establishing contact with interior surfaces of the sleeve so as to maintain the article and the sleeve in frictional engagement to form a pack.
The sleeve forming arrangement is operable to form a collapsed continuous tube from a web of packaging material, such as paper, with the edge areas of the web being formed in an overlapping relationship. A bonding agent, such as glue, is applied between the overlapping edge areas of the web to form the collapsed tube. The tube is advanced onto a sleeve former, which functions to erect the sleeve as the sleeve is advanced to a location adjacent the loading area. After the collapsed tube is formed, the collapsed tube passes through a perforating assembly that forms transverse perforations at predetermined intervals along the length of the collapsed tube. When the sleeve is advanced from the former onto the compressed article at the loading area, advancement of the sleeve separates the sleeve from the next adjacent sleeve by breaking the perforations, and the next adjacent sleeve is then advanced onto the former for application to a subsequently supplied compressed article.
The former includes a downstream section that forms the sleeve to the desired erected configuration adjacent the loading area. The downstream section of the former is supported in a manner that enables the sleeve to be advanced onto the downstream section and subsequently off the downstream section for application to the compressed article. In a preferred embodiment, the downstream section of the former is supported using a magnetic support arrangement, which enables the sleeve to be advanced onto the downstream section of the former, and discharged from the downstream section of the former onto the compressed article.
The sleeve advancing arrangement may be in the form of spaced apart drive rollers that engage the sleeve so as to advance the sleeve in a downstream direction. The former preferably includes inner rollers, each of which forms a nip with one of the drive rollers, so that the drive rollers and the inner rollers cooperate to pinch the walls of the sleeve located between the drive roller and the inner roller to advance the sleeve onto the downstream section of the former. In one form, the magnetic support arrangement is in the form of magnets on the drive rollers and on the inner rollers that support the sleeve forming arrangement between the drive rollers. Additional pairs of inner and outer rollers may be provided for advancing the sleeve, and may include additional inner and outer magnets that support the downstream section of the former. The magnetic support arrangement may further include transversely oriented inner and outer axial positioning magnetic members that cooperate to maintain the downstream section of the former in a predetermined axial position.
The article supply arrangement may be in the form of a carriage that is movable between an article supply area and the loading area. The article supply arrangement includes at least one movable member that is operable to compress the article, and that maintains compression on the article as the sleeve is advanced onto the compressed article at the loading area. The article supply arrangement has relatively thin walls that maintain compression on the article at the loading area, and that are withdrawn from between the article and the interior surfaces of the sleeve as the article supply arrangement is moved away from the loading area.
The invention also contemplates a method of packaging a compressible article in a band or sleeve of packaging material, substantially in accordance with the foregoing summary.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.